Field of the Invention (Technical Field):
The present invention relates to a method of preparing wood and plastic to produce a composite material.
The present invention comprises a composite material comprising natural material particles and plastic wherein the natural material particles comprise an average size of less than approximately 0.25 inch. In a preferred embodiment, the particles comprise at least one dimension that is less than or equal to 0.25 inch. In a preferred embodiment of the present invention, the natural material particles comprise average moisture of less than approximately 5%, preferably less than approximately 2% and most preferably an average moisture of less than approximately 1%. According to the present invention, in a preferred embodiment, the natural material particles comprise at least one member selected from the group consisting of trunk particles, bark particles, branch particles, leaf particles, root particles, and needle particles. In a preferred embodiment, natural material particles comprise one-seed juniper particles and/or ponderosa pine particles.
According to the present invention, natural material particles optionally comprise: a random orientation in the composite material; a process-related orientation; or a combination of random and process-related orientations. For example, extrusion processes inherently involve fluid dynamics, which may orient natural particles in the composite material.
In a preferred embodiment of the present invention, the natural material particles comprise an average particle size of less than approximately 0.125 inch, preferably less than approximately 0.0625 inch, and more preferably less than or equal to approximately 0.03125 inch. It is understood that in several embodiments, natural material particles comprise unequal dimensions, for example, but not limited to, a length greater than a width. In such embodiments, a particle size refers to at least one dimension comprising the specified size. For example, a particle comprising a width of approximately 0.03 inch and a length greater than approximately 0.04 inch is capable of passing through a screen opening, or the like, of at least 0.03 inch.
In a preferred embodiment of the present invention, plastic comprises a thermoplastic. In a preferred embodiment of the present invention, plastic comprises at least one plastic selected from the group consisting of polypropylene, polyethylene, polyurethane and polyvinylchloride. In a preferred embodiment, plastic comprises recycled plastic, virgin plastic and/or a combination of both.
In a preferred embodiment of the present invention, the composite material comprises at least approximately 20% by weight of natural material particles, preferably at least approximately 40% by weight of natural material particles and more preferably at least approximately 50% by weight of natural material particles. In a preferred embodiment, the composite material comprises of at least approximately 20% by weight of plastic, preferably at least approximately 40% by weight of plastic, and more preferably at least approximately 50% by weight of plastic. In a preferred embodiment, the composite material comprises a contiguous plastic layer comprising included natural material particles.
The present invention also comprises a method of preparing natural material particles for making a composite material. According to a preferred embodiment the method comprises the steps of logging natural material; grinding logged natural material; screening ground natural material; and grinding screened natural material. In a preferred embodiment, the first grinding step comprises grinding the natural material to a maximum particle dimension of less than approximately 12 inches. In a preferred embodiment, the method further comprises a washing step before the second grinding step and/or a drying step before the second grinding step. According to a preferred embodiment, the second grinding step comprises grinding the natural material to a maximum particle size of less than approximately 0.5 inches. In a preferred embodiment, the method further comprises a chunking step before the first grinding step, a screening step additionally comprising a washing step, a flaking step before the second grinding step, and/or a sifting step after the second grinding step. A sifting step is useful for, but not limited to, producing material comprising a more uniform size.
The present invention also comprises a press method of making a composite material. In a preferred embodiment, the method comprises the steps of: providing a frame; loading natural material and plastic into the frame; and applying heat and pressure to the natural material and plastic in the frame. According to a preferred embodiment, the method further comprises a step of removing the composite material from the frame after the applying step, a step of inserting a forming box into the frame, and/or a step of adjusting the packing of the natural material and plastic before the applying step.
In a preferred embodiment, the applying step comprises applying heat to reach a temperature of at least approximately 300xc2x0 F. and/or the applying step comprises applying a pressure of at least approximately 4 psig. In a preferred embodiment, the applying step comprises applying heat to reach a temperature of approximately 400xc2x0 F. and/or the applying step comprises applying a pressure of approximately 8 psig.
The present invention also comprises an extrusion method of making composite material. According to a preferred embodiment, the method comprises the steps of: feeding natural material and plastic into an extruder; heating the natural material and plastic in the extruder; and extruding composite material comprising the natural material and plastic from the extruder. In a preferred embodiment, the extruding step comprises extruding composite material onto a film. In another preferred embodiment, the method further comprises a step of rolling extruded composite material between two rollers and/or a step of cooling extruded material.
The present invention also comprises a method of making composite material comprising the steps of: processing natural material; and making composite material comprising natural material and plastic wherein making comprises at least one method selected from the group consisting of press methods and extrusion methods.
A primary object of the present invention is to produce a wood and plastic composite material.
A primary advantage of the present invention is economy of preparation of wood and plastic raw materials and production of a composite material comprising the same.